Endotoxin, also known as lipopolysaccharide (LPS), is an integral component of the Gram-negative bacterial cell membrane and is responsible for many, if not all, of the toxic effects that occur during Gram-negative bacterial sepsis. LPS is a mixture of glycolipids consisting of a variable polysaccharide domain covalently bound to a conserved glucosamine-based phospholipid known as lipid A. LPS directly stimulates host monocytes and macrophages to secrete a wide array of inflammatory cytokines that include tumor necrosis factor-I (TNF-I), interleukin-1 (IL-1), and interleukin-8 (IL-8). Excessive release of these cytokines by host macrophages contributes to organ failure and death that occur after episodes of Gram-negative bacterial sepsis.